Effects of imazodan and dazoxiben on cAMP levels and PGI2 production in cultured bovine aortic endothelial cells

We have investigated the effects of imazodan, a potent inhibitor of phosphodiesterase III (PDE III) and dazoxiben, a selective inhibitor of thromboxane synthetase on cAMP levels and PGI2 production in cultured bovine aortic endothelial cells by radioimmunoassay. When cultured endothelial cells were incubated with imazodan, intracellular levels of cAMP were increased in a dose-dependent manner. PGI2 production induced by arachidonic acid (AA) was not affected by imazodan 0.1-10 mumol/L. But imazodan 100 mumol/L caused a 35% inhibition of PGI2 production. In the presence of AA, dazoxiben could also elevate intracellular levels of cAMP. Furthermore, dazoxiben 1-10 mumol/L caused a marked increase in PGI2 production, but 1000 mumol/L inhibited PGI2 production.